The mystery of how our cells respond to everything from taste to light to hormones like adrenalin is the subject of this year's Nobel Prize for Chemistry.

Two US scientists - Robert Lefkowitz and Brian Kobilka - have been given the award for their research into what are known as 'receptors' - parts of the cell that are responsible for communication with the outside world. It's with the help of receptors that medications are able to have an effect.

For many years one of the great puzzles of the human body was how light and flavour and smell could be communicated to your cells - and how hormones such as adrenalin or medicines could reach through the walls of the cells to the vital mechanisms inside.

Robert Lefkowitz was the first to discover the tiny components which performed this role - and they became known as 'G-protein-coupled receptors'.

Finding them has proved essential to working out how and why our cells can respond to a sudden fright or a medical intervention - it's now known that half of all medications work by communicating through these particular receptors.

In the same lab in North Carolina, Brian Kobilka went further by locating the genes that give rise to these crucial parts of the cell. According to the Nobel judges, the work of these two men and their teams has revealed the 'finely-tuned regulation of the cells that life requires'.

And to help everyone understand the significance of these discoveries, they offer this explanation: 'next time you get scared, savour the taste of good food or simply gaze at the stars in the sky, give a thought to your G-protein-coupled receptors.without them chaos would reign.